Fuel lubricity from blends of lubricity improvers and corrosion inhibitors or stability additives

ABSTRACT

It has been discovered that compositions that are blends or mixtures of certain lubricity additives and corrosion inhibitors and/or stability additives can serve as improved lubricity additive compositions in distillate fuels. The corrosion inhibitors may include, but are not necessarily limited to, saturated or unsaturated monomer, dimer, and trimer fatty acids, succinic acids, imidazolines, and mixtures thereof. Suitable stability additives include, but are not necessarily limited to, amines, amides, amine/aldehyde condensates, polymer dispersants, and mixtures thereof, where the stability additive is different from the lubricity additive. It has been surprisingly discovered that less lubricity additive may be used in the compositions when the stability additive or corrosion inhibitor is present to achieve the same lubricity result, as compared with compositions that do not contain a stability additive or corrosion inhibitor, yet the same total amount of additive composition.

FIELD OF THE INVENTION

The present invention relates to lubricity additives for distillatefuels, and more particularly relates, in one embodiment to the co-use ofcorrosion inhibitors and/or stability additives together with lubricityadditives for hydrocarbon fuels.

BACKGROUND OF THE INVENTION

It is well known that in many engines the fuel is the lubricant for thefuel system components, such as fuel pumps and injectors. Many studiesof fuels with poor lubricity have been conducted in an effort tounderstand fuel compositions that have poor lubricity and to correlatelab test methods with actual field use. The problem is general to dieselfuels, kerosene and gasolines, however, most of the studies haveconcentrated on the first two hydrocarbons.

Previous work has shown that saturated, monomeric and dimeric, fattyacids of from 12 to 54 carbon atoms used individually give excellentperformance as fuel lubricity aids in diesel fuels. A number of otherkinds of lubricity additives are also known. Since the advent of lowsulfur diesel fuels in the early 1990s, relatively large amounts ofthese lubricity additives have been used to provide a fuel that does notcause excessive wear of engine parts. Thus, it would be desirable if away to reduce the amount of lubricity additives could be devised thatwould provide equivalent or superior performance of the fuels.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide fuellubricity compositions that improves lubricity over conventionaladditives.

It is another object of the present invention to provide fuel lubricitycompositions that permit lower lubricity additive treatment levels whileproviding the equivalent lubricity performance.

In carrying out these and other objects of the invention, there isprovided, in one form, a composition for improving the lubricity ofdiesel and kerosene distillate fuels having 0.2 wt % or less sulfur thathas (a) at least one lubricity additive that can be an ester-basedlubricity additive and/or an amide-based lubricity additive. Suitableester-based lubricity additives include, but are not necessarily limitedto reaction products of saturated, unsaturated, mixed saturated andunsaturated, mono-, di- and tri-carboxylic acids having from 12 to 72carbon atoms with alcohols, glycols, polyglycols, and mixtures thereof.Suitable amide-based lubricity additives include, but are notnecessarily limited to reaction products of saturated, unsaturated,mixed saturated and unsaturated and aryl substituted carboxylic acidshaving from 12 to 72 carbon atoms with amines selected from the groupconsisting of alkanolamines, alkylamines, cyclic amines, aromaticamines, polyamines, and mixtures thereof. The composition also includes(b) at least one second additive that may be a corrosion inhibitorand/or a stability additive. Suitable corrosion inhibitors include, butare not necessarily limited to saturated or unsaturated monomer, dimer,and trimer fatty acids, succinic acids, imidazolines, and mixturesthereof. Suitable stability additives include, but are not necessarilylimited to hindered primary, secondary, and tertiary amines, amides,amine/aldehyde condensates, polymer dispersants, and mixtures thereof,where the stability additive is different from the lubricity additive.

DETAILED DESCRIPTION OF THE INVENTION

New compositions have been discovered which contain corrosion inhibitorsand/or stability additives along with lubricity additives are useful asfuel lubricity aids, and which can offer the same fuel lubricityproperties with reduced amounts of fuel lubricity additives. The use ofthe corrosion inhibitors and/or stability additives together withcertain fuel lubricity additives creates a synergistic effect thatpermits reduced amounts of the fuel lubricity additives to be used, yetachieve comparable properties to compositions that do not contain thecorrosion inhibitors and/or stability additives.

The invention relates to lubricity additive compositions for distillatefuels, as contrasted with products from resid. In the context of thisinvention, distillate fuels include, but are not necessarily limited todiesel fuel, kerosene, gasoline and the like. It will be appreciatedthat distillate fuels include blends of conventional hydrocarbons meantby these terms with oxygenates, e.g. alcohols, such as methanol, andother additives or blending components presently used in thesedistillate fuels, such as MTBE (methyl-tert-butyl ether), or that may beused in the future. In one non-limiting embodiment of the invention, theinvention relates to low sulfur fuels, which are defined as having asulfur content of 0.2% by weight or less, and in another non-limitingembodiment as having a sulfur content of about 0.0015 wt. % or less—suchas the so-called “ultra low sulfur” fuels. Particularly preferredhydrocarbon fuels herein are diesel and kerosene.

Generally, in one embodiment of the invention the composition forimproving the lubricity of distillate fuels is a mixture or blend of atleast one first additive, that is a lubricity additive and at least onesecond additive. The lubricity additive may be either an ester-basedlubricity additive or an amide-based lubricity additive or mixtures ofboth. Suitable ester-based lubricity additive include, but are notnecessarily limited to reaction products of saturated, unsaturated,mixed saturated and unsaturated mono-, di- and tri-carboxylic acidshaving from 12 to 72 carbon atoms with alcohols, glycols, polyglycols,and mixtures thereof. These esters may be prepared by known techniques.Specific examples of suitable ester-based lubricity additives include,but are not necessarily limited to, a dimer fatty acid copolymer withethyleneglycol-polyester, and glycerin monoleate, dioleate, andtrioleate, and the like.

More specific examples of suitable saturated, unsaturated, mixedsaturated and unsaturated mono-, di- and tri-carboxylic acids havingfrom 12 to 72 carbon atoms suitable to prepare the ester-based lubricityadditives of this invention include, but are not necessarily limited to,Arizona Unidyme 35 (unsaturated), Uniqema Pripol 1009 (saturated), oleicacid, stearic acid, and mixtures thereof. It should be understood thatthe definition of these suitable carboxylic acids include so-calledsynthetic acids, which may include, but are not necessarily limited toacids such as xylylstearic acid, phenylstearic acid, tolylstearic acid,ricinoleic acid, hydrogenated monomer and oligomer fatty acids, andaromatic substituted fatty acids and mixtures thereof. Further, morespecific examples of suitable alcohols, glycols, and polyglycols(hydroxyl compounds) include, but are not necessarily limited to,ethylene glycol, propylene glycol, glycerol, C4 to C30 linear andbranched alcohols, oxyalkylated linear and branched alcohols, andpolyhydric alcohols prepared from oxyalkylation of alkylphenolformaldehyde resins and mixtures thereof. By the term “polyglycols” ismeant polymers of glycols, where the polymer has 2 to 40 hydroxylgroups.

In another non-limiting embodiment of the invention, the ester lubricityadditives may be polymeric, such as the dimer fatty acid copolymer withethylene glycol lubricity additives described above or simple monomeracid esters (oleic, tallow, coco, etc.) made with glycols. It shouldalso be understood that the lubricity additive esters of this inventioninclude esters prepared by the condensation of a monomer fatty acid withtriethanolamine to form an amino-substituted ester of the generalstructure:R—C(O)—OCH₂CH₂—N(CH₂CH₂OH)₂  (I)where R=C12 to C₁₋₈ alkyl or alkenyl groups.

The suitable amide-based lubricity additives may include, but are notnecessarily limited to reaction products of saturated, unsaturated,mixed saturated and unsaturated, and aryl substituted carboxylic acidshaving from 12 to 72 carbon atoms with amines selected from the groupconsisting of alkanolamines, alkyl-amines, cyclic amines, aromaticamines, and mixtures thereof. In one non-limiting embodiment of theinvention, the amines have a generally low molecular weight, forinstance from about 100 to about 500 weight average molecular weight.The saturated, unsaturated, mixed saturated and unsaturated, and arylsubstituted carboxylic acids having from 12 to 72 carbon atoms used tomake the amide-based lubricity additives may be the same carboxylicacids as those used in the preparation of the ester-based lubricityadditives described above. More specific examples of suitablealkanolamines, alkylamines, cyclic amines, aromatic amines, etheramines,polyamines, and polyalkylene amines include, but are not necessarilylimited to, diethanolamine, dibutanolamine, diisopropanolamine,diethylamine, cyclohexylamine, isopropylamine, hindered primary amines(e.g. Rohm & Haas Primene 81 R and Primene RB3), andbis-N,N′-dibutylaminomethane and mixtures thereof. In one non-limitingembodiment of the invention, the amides should be hydroxyalkyl-substituted rather than just alkyl-substituted (that isalkanolamides rather than alkyl-amides). The processes and conditionsused to make the amide-based lubricity additives are known to those ofordinary skill in the art. Specific examples of suit-able amide-basedlubricity additives include, but are not necessarily limited to,alkanolamides of tall oil fatty acid, and the like.

As noted, the second additive may be a corrosion inhibitor or astability additive. Suitable corrosion inhibitors include but are notnecessarily limited to saturated or unsaturated monomer, dimer, andtrimer fatty acids, succinic acids, imidazolines, and mixtures thereof.More particular examples of suitable corrosion inhibitors include, butare not necessarily limited to, dimer and trimer fatty acids that arethe reaction products of C12-C22 saturated and unsaturated monomer acidsto produce dimers and trimers, C12-C22 saturated and unsaturated monomerfatty acids and mixtures thereof, tetrapropenylsuccinic acid, andreaction products between C12-C22 saturated and unsaturated monomerfatty acids with blends of diethylenetriamine or aminoethylethanolamine.

The monomeric fatty acid components may be a saturated, monomeric fattyacid having from 12 to 22 carbon atoms, an unsaturated, monomeric fattyacid having from 12 to 22 carbon atoms, or a synthetic monomeric fattyacid having from 12 to 50 carbon atoms. In one general embodiment of theinvention, a synthetic monomeric fatty acid is any monomeric fatty acidwithin the given carbon number range that does not occur in nature. Inone non-limiting embodiment of the invention, a synthetic monomericfatty acid is one that results from the modification of a natural fattyacid by a process including, but not limited to, alkylation,hydrogenation, arylation, isomerization or combinations of thesemodifications. In another, non-limiting embodiment of the invention, thesynthetic monomeric fatty acid is formed by dimerizing any of the anunsaturated, monomeric fatty acids having from 12 to 22 carbon atomsmentioned above, and then hydrogenating them.

More specific examples of suitable saturated, monomeric fatty acidsinclude, but are not limited to, lauric acid (dodecanoic acid); myristicacid (tetradecanoic acid); palmitic acid (hexadecanoic acid); stearicacid (octadecanoic acid); and the like. Specific examples of suitableunsaturated, monomeric fatty acids include, but are not limited to,oleic acid (cis-9-octadecenoic acid); tall oil fatty acid (e.g. WestvacoL-5); and the like. Specific examples of suitable synthetic, monomericfatty acids include, but are not limited to, Union Camp Century 1105 andthe like.

The oligomeric fatty acid components may be a saturated, oligomericfatty acid having from 24 to 72 carbon atoms, or an unsaturated,monomeric fatty acid having from 24 to 72 carbon atoms. In one generalembodiment of the invention, the oligomeric fatty acids may be made bydimerizing or trimerizing any of the unsaturated monomeric acidssuitable for the monomeric fatty acid component described above.

Specific examples of suitable saturated, oligomeric fatty acids include,but are not limited to, dimer acid (e.g. Unichema Pripol 1009); and thelike. Specific examples of suitable unsaturated, oligomeric fatty acidsinclude, but are not limited to, dimer acid (e.g. Westvaco DTC-595);trimer acid (e.g. Westvaco DTC-195); and the like. In one embodiment ofthe invention it is preferred that the oligomeric fatty acid componentbe a dimer, although trimers are acceptable.

Suitable stability additives include antioxidants not necessarilylimited to amines, amides, amine/aldehyde condensates, hindered primaryamines (e.g. Rohm & Haas Primene 81R) and hindered tertiary amines (e.g.dimethylcyclohexyl amine) and mixtures thereof, where the stabilityadditive is different from the lubricity additive defined above. Moreparticular examples of suitable stability additives include, but are notnecessarily limited to, hindered C8-C22 primary, secondary, or tertiaryamines, alkanolamides made from diethanolamine and fatty acids (such asthose described above), condensates of C4-C12 alkyl phenols withaldehydes and alkyldiamines, and mixtures thereof. By “hindered C8-C22primary amines” is meant primary amines that are sufficiently branchedto provide at least some degree of steric hindrance. Suitable stabilityadditives also include diaminomethanes, particularlybis-dialkyldiaminomethanes of U.S. Pat. No. 4,978,366, hereinincorporated by reference.

In one non-limiting embodiment of the invention, the proportion of (a)lubricity additive in the total distillate fuel ranges from about 10 toabout 200 ppm, whereas the proportion of the at least one (b) secondadditive ranges from about 1 to about 60 ppm. The proportions for thelubricity additive (a) are for the total amount of lubricity additives(a), should more than one type be used. It should be noted that thenormal proportions of lubricity additives (a) typically range from aslittle as about 20 ppm to as much as 400 ppm. Thus, it may be seen thatthe lubricity additive (a) proportion may be reduced approximately inhalf using the synergistic composition of this invention, in onenon-limiting embodiment thereof.

The proportions for the second additive (b) are for the total amount ofsecond additives, should more than one type be used. In anothernon-limiting embodiment of the invention, the proportion of secondcomponent (b) in the distillate fuel ranges from about 10 to about 30ppm.

It will be appreciated that the invention herein also encompassesdistillate fuels containing the compositions of this invention as wellas methods of improving the lubricity properties of distillate fuelsusing the compositions of this invention.

Typically, a solvent is preferably used in the compositions of theinvention, where the solvent may be aromatic solvents and pureparaffinic solvents. Aromatic solvents are particularly preferred. Theproportion of solvent in the total fuel lubricity aid composition mayrange from about 0 to 90 weight %. The use of a solvent is optional.Specific examples of suitable solvents include, but are not limited toparaffins and cycloparaffins, aromatic naphtha; kerosene; diesel;gasoline; xylene; toluene, alcohols; and the like.

Other, optional components of the distillate fuels of this invention innon-limiting embodiments may include, but are not necessarily limited todetergents, pour point depressants, cetane improvers, dehazers, coldoperability additives, conductivity additives, biocides, dyes, andmixtures thereof. In another non-limiting embodiment of the invention,water is explicitly absent from the inventive composition.

The invention will be illustrated further with respect to the followingnon-limiting Examples that are included only to further illuminate theinvention and not to restrict it.

EXAMPLES 1-3

Samples 1 through 3 were tested in the diesel fuels noted according toASTM-6079 High Frequency Reciprocating Rig (HFRR) specifications at 60°C. The results are presented in Table I. Usually, a level of 450 μm orbelow is considered a “good” WSD value to have for a fuel, although someareas use a 460 μm level. TABLE I WSD Results Lubricity Dose, SecondDose, WSD, Ex. Fuel additive ppm additive ppm microns 1A CaliforniaAdditive A 100 — — 576 ULSD 1B California Additive A  80 Additive B 20302 ULSD 2A California Additive A 100 — — 576 ULSD 2B CaliforniaAdditive A  80 Westvaco 20 490 ULSD DTC-595 3A European Additive A 200 —— 515 ULSD 3B California Additive A 180 Additive C 20 423 ULSD

Definitions for Examples 1-3:

-   California ULSD An ultra low sulfur diesel fuel used as a standard    in California.-   European ULSD An ultra low sulfur diesel fuel used as a standard in    Europe.-   Additive A Alkanolamide lubricity additive available from Baker    Petrolite.-   Additive B Alkyl phenol/aldehyde polyamine stability additive    available from Baker Petrolite.-   Additive C Dimer fatty acid/alkyl succinic acid blend corrosion    inhibitor available from Baker Petrolite.-   DTC-595 Dimer fatty acid corrosion inhibitor available from    Westvaco.

As can be seen in Table I, the wear scar data obtained using theinventive compositions of Examples 1B, 2B and 3B that containedstability additives or corrosion inhibitors was better than thatobtained using conventional lubricity additives alone, even though thesame total proportions of additives was used. These results demonstratethat there is a synergistic effect occurring that would allow lesslubricity additive to be used when the second additive is present, toachieve the same WSD result.

In the foregoing specification, the invention has been described withreference to specific embodiments thereof, and has been demonstrated aseffective for improving the lubricity of fuels. However, it will beevident that various modifications and changes can be made theretowithout departing from the broader spirit or scope of the invention asset forth in the appended claims. Accordingly, the specification is tobe regarded in an illustrative rather than a restrictive sense. Forexample, specific combinations of second additives (corrosion inhibitorsand/or stability additives) falling within the claimed parameters, butnot specifically identified or tried in a particular composition toimprove the lubricity of fuels herein, are anticipated to be within thescope of this invention. It is anticipated that the compositions of thisinvention may also impart to the engines in which they are used as fuellubricity aids, greater horsepower, lower emissions and better fueleconomy as a result of less friction, whether they are used in diesel orgasoline engines.

It will be appreciated, of course, that the corrosion inhibitoradditives of this invention will also have desirablecorrosion-inhibiting properties in the ultimate distillate fuel. Inturn, the stability additive will also have the ability to improve thestability of the distillate fuel, as well as the other beneficialproperties of the invention herein.

1. A composition for improving the lubricity of diesel and kerosenedistillate fuels having 0.2 wt % or less sulfur comprising: (a) at leastone lubricity additive selected from the group consisting of ester-basedlubricity additives selected from the group consisting of reactionproducts of: carboxylic acids selected from the group consisting ofsaturated, unsaturated, mixed saturated and unsaturated di- andtri-carboxylic acids having from 12 to 72 carbon atoms with hydroxylcompounds selected from the group consisting of alcohols, glycols,polyglycols, and mixtures thereof; and amide-based lubricity additivesselected from the group consisting of reaction products of: carboxylicacids selected from the group consisting of saturated, unsaturated,mixed saturated and unsaturated, and aryl substituted carboxylic acidshaving from 12 to 72 carbon atoms with amines selected from the groupconsisting of alkanolamines, alkylamines, cyclic amines, aromaticamines, polyamines, and mixtures thereof; and (b) at least one secondadditive selected from the group consisting of corrosion inhibitorsselected from the group consisting of saturated or unsaturated monomer,dimer, and trimer fatty acids, succinic acids, imidazolines, andmixtures thereof; stability additives selected from the group consistingof hindered primary, secondary and tertiary amines, amides,amine/aldehyde condensates, and mixtures thereof, where the stabilityadditive is different from the lubricity additive; and mixtures thereof.2. The composition of claim 1 where the corrosion inhibitors are furtherselected from the group consisting of dimer and trimer fatty acids thatare the reaction products of C12-C22 saturated and unsaturated monomeracids to produce dimers and trimers, C12-C22 saturated and unsaturatedmonomer fatty acids and mixtures thereof, tetrapropenylsuccinic acid,and reaction products between C12-C22 saturated and unsaturated monomerfatty acids with blends of diethylenetriamine or aminoethylethanolamine.3. The composition of claim 1 where the stability additives are furtherselected from the group consisting of hindered C8-C22 primary,secondary, or tertiary amines, alkanolamides made from diethanolamineand fatty acids, condensates of C4-C12 alkyl phenols with aldehydes andalkyldiamines, and diaminomethanes and mixtures thereof.
 4. Thecomposition of claim 1 where the proportion of lubricity additive (a)ranges from about 10 to about 400 ppm; the proportion of the at leastone second additive (b) ranges from about 1 to about 60 ppm; based onthe distillate fuel.
 5. A composition for improving the lubricity ofdiesel and kerosene distillate fuels having 0.2 wt % or less sulfurcomprising: (a) at least one lubricity additive selected from the groupconsisting of ester-based lubricity additives selected from the groupconsisting of reaction products of: carboxylic acids selected from thegroup consisting of saturated, unsaturated, mixed saturated andunsaturated di- and tri-carboxylic acids having from 12 to 72 carbonatoms with hydroxyl compounds selected from the group consisting ofalcohols, glycols, polyglycols, and mixtures thereof; and amide-basedlubricity additives selected from the group consisting of reactionproducts of: carboxylic acids selected from the group consisting ofsaturated, unsaturated, mixed saturated and unsaturated, and arylsubstituted carboxylic acids having from 12 to 72 carbon atoms withamines selected from the group consisting of alkanolamines, alkylamines,cyclic amines, aromatic amines, polyamines, and mixtures thereof; and(b) at least one second additive selected from the group consisting ofcorrosion inhibitors selected from the group consisting of dimer andtrimer fatty acids that are the reaction products of C12-C22 saturatedand unsaturated monomer acids to produce dimers and trimers, C12-C22saturated and unsaturated monomer fatty acids and mixtures thereof,tetrapropenylsuccinic acid, and reaction products between C12-C22saturated and unsaturated monomer fatty acids with blends ofdiethylenetriamine or aminoethylethanolamine; stability additivesselected from the group consisting of; hindered C8-C22 primary,secondary, or tertiary amines, alkanolamides made from diethanolamineand fatty acids, condensates of C4-C12 alkyl phenols with aldehydes andalkyldiamines, and diaminomethanes and mixtures thereof; and mixturesthereof.
 6. A distillate fuel having improved lubricity comprising: (A)a hydrocarbon having 0.2 wt. % or less sulfur selected from the groupconsisting of diesel fuel and kerosene; and (B) an effective amount of acomposition for improving the lubricity of distillate fuels comprising:(a) at least one lubricity additive selected from the group consistingof ester-based lubricity additives selected from the group consisting ofreaction products of: carboxylic acids selected from the groupconsisting of carboxylic acids selected from the group consisting ofsaturated, unsaturated, mixed saturated and unsaturated mono-, di- andtri-carboxylic acids having from 12 to 72 carbon atoms with hydroxylcompounds selected from the group consisting of alcohols, glycols,polyglycols, and mixtures thereof; and amide-based lubricity additivesselected from the group consisting of reaction products of: carboxylicacids selected from the group consisting of saturated, unsaturated,mixed saturated and unsaturated, and aryl substituted carboxylic acidshaving from 12 to 72 carbon atoms with amines selected from the groupconsisting of alkanolamines, alkylamines, cyclic amines, aromaticamines, polyamines and mixtures thereof; and (b) at least one secondadditive selected from the group consisting of corrosion inhibitorsselected from the group consisting of saturated or unsaturated monomer,dimer, and trimer fatty acids, succinic acids, imidazolines, andmixtures thereof; stability additives selected from the group consistingof hindered primary, secondary, and tertiary amines, amides,amine/aldehyde condensates, diaminomethanes, polyamines, and mixturesthereof, where the stability additive is different from the lubricityadditive; and mixtures thereof.
 7. The distillate fuel of claim 6 wherethe corrosion inhibitors are further selected from the group consistingof dimer and trimer fatty acids that are the reaction products ofC12-C22 saturated and unsaturated monomer acids to produce dimers andtrimers, C12-C22 saturated and unsaturated monomer fatty acids andmixtures thereof, tetrapropenylsuccinic acid, and reaction productsbetween C12-C22 saturated and unsaturated monomer fatty acids withblends of diethylenetriamine or aminoethylethanolamine.
 8. Thedistillate fuel of claim 6 where the stability additives are furtherselected from the group consisting of hindered C10-C22 primary,secondary, or tertiary amines, alkanolamides made from diethanolamineand fatty acids, condensates of C4-C12 alkyl phenols with aldehydes andalkyldiamines, and diaminomethanes and mixtures thereof.
 9. Thedistillate fuel of claim 6 where the proportion of lubricity additive(a) ranges from about 10 to about 400 ppm; the proportion of the atleast one second additive (b) ranges from about 1 to about 60 ppm; basedon the distillate fuel.
 10. A method for improving the lubricity ofdistillate fuel comprising: (A) providing a hydrocarbon having 0.2 wt. %or less sulfur selected from the group consisting of diesel fuel andkerosene; and (B) adding to the hydrocarbon an effective amount of acomposition for improving the lubricity of the hydrocarbon, where thecomposition comprises: (a) at least one lubricity additive selected fromthe group consisting of ester-based lubricity additives selected fromthe group consisting of reaction products of; carboxylic acids selectedfrom the group consisting of saturated, unsaturated, mixed saturated andunsaturated, and aryl substituted mono-, di- and tri-carboxylic acidshaving from 12 to 72 carbon atoms with hydroxyl compounds selected fromthe group consisting of alcohols, glycols, polyglycols, and mixturesthereof; and amide-based lubricity additives selected from the groupconsisting of reaction products of: carboxylic acids selected from thegroup consisting of saturated, unsaturated, mixed saturated andunsaturated, and aryl substituted carboxylic acids having from 12 to 72carbon atoms with amines selected from the group consisting ofalkanolamines, alkylamines, cyclic amines, aromatic amines, and mixturesthereof; and (b) at least one second additive selected from the groupconsisting of corrosion inhibitors selected from the group consisting ofsaturated or unsaturated monomer, dimer, and trimer fatty acids,succinic acids, imidazolines, and mixtures thereof; stability additivesselected from the group consisting of amines, amides, amine/aldehydecondensates, hindered primary, secondary, and tertiary amines, andmixtures thereof, where the stability additive is different from thelubricity additive; and mixtures thereof.
 11. The method of claim 10where in adding the composition, the corrosion inhibitors are furtherselected from the group consisting of dimer and trimer fatty acids thatare the reaction products of C14-C22 saturated and unsaturated monomeracids to produce dimers and trimers, C12-C22 saturated and unsaturatedmonomer fatty acids and mixtures thereof, tetrapropenylsuccinic acid,and reaction products between C12-C22 saturated and unsaturated monomerfatty acids with blends of diethylenetriamine or aminoethylethanolamine.12. The method of claim 10 where in adding the composition, thestability additives are further selected from the group consisting ofhindered C10-C22 primary amines, alkanolamides made from diethanolamineand fatty acids, condensates of C4-C12 alkyl phenols with aldehydes andalkyldiamines.
 13. The method of claim 9 where in adding thecomposition, the proportion of lubricity additive (a) ranges from about10 to about 400 ppm; the proportion of the at least one second additive(b) ranges from about 1 to about 60 ppm; based on the distillate fuel.